Session 10 (Haemoglobin And Myoglobin) Flashcards
What is the physiological role of haemoglobin and myoglobin?
Transport O2 around the body
What amino acid residue attaches to the haem group?
Histidine
Which is more efficient at carrying O2, Haemoglobin or myoglobin? And why?
Haemoglobin, because it has a lower affinity for O2 at the PO2 of the tissues meaning it releases the O2 with greater ease
What graph does myoglobin produce?
Hyperbolic
Only carries 1 O2, either 0% or 100% saturated
What graph does haemoglobin produce? Why?
Sigmoidal
Performs cooperative binding- binding of one O2 molecule promotes binding of subsequent molecules
What is a benefit of cooperative binding?
Haemoglobin is more sensitive to small changes in 02 conc
What is BPG?
2,3 bisphosphoglycerate
How does BPG effect Haemoglobin?
Makes it more efficient at O2 transport
When might [BPG] increase?
At high altitudes, promotes O2 release in tissue
What does BPG do in general?
Lowers affinity (shifts graphs to right)
What is the bohr effect?
H+ and CO2 binding to Haemoglobin
How might the Bohr effect be a good thing?
CO2 and H+ lowers pH
therefore Hb has a lower affinity for O2
O2 released in tissue
Tissue is able to keep metabolising
What effect does CO have on Hb’s affinity for unaffected subunits?
Increases it
Why is it good for HbF to have a higher affinity for O2 than HbA?
Allows transfer of O2 to foetal blood supply from mother
What causes sickle cell anaemia?
The mutation changing glutamate to valine
(Hydrophilic to hydrophobic)
The hydrophobic nature of valine joins to other hydrophobic amino acids and causes Hb to join together into a polymer
